After just 65 feet it’s possible to see the famous Stone Age bulls on the wall … if you can find your way in, that is. The cave has been closed to the public since the 1963.
Just 100 feet into this grotto, you’ll start to see evidence of Arachnocampa luminosa—or glowworms as they’re more commonly known.
One of the longest cave systems in the world at 140 miles, it’s beautiful: Think 20-foot gypsum chandeliers and cave pearls.
After a quarter mile of transverse descent, you come to the eerie stalactite formation known as the Salle des Treize.
Known as Elsa’s Ice Palace, only the first half-mile of this pure ice cave is accessible. Beyond that it’s Elsa only.
Dug in 1943 by Polish slave laborers who, to the Nazis’ chagrin, not only refused to die but actually got stronger. All as a result of the mountain’s (slightly controversial) radioactive healing powers.
Jungle gym: Almost four miles into this vast cave you’re confronted with a wall 200 feet high, which has only just been conquered by mountaineers.